A light control material capable of controlling the light transmittance in a specific wavelength range has been utilized for controlling transmitted light or for controlling color by interrupting light of a specific wavelength, and applied in various fields including, for example, interior materials, construction materials, electronic parts, and the like. Furthermore, in these days, materials capable of controlling the light transmittance in the infrared range have attracted attention and a variety of investigations on such materials have been conducted.
As examples of the light control materials of this kind, Patent Document 1 and Patent Document 2 propose a light control material containing a suspension of light-polarizing particles and a polymer resin. In a light control body formed by using the light control material, the polarizing particles are disposed to form a translucent form in response to an electric field. However, this kind of light control material has a problem that it is not possible to optionally and easily control the light transmittance in an arbitrary wavelength range among a sufficiently wide wavelength range from the visible light range to the near-infrared range.
Patent Document 3 and Patent Document 4 disclose a heat ray shielding light control material which is characterized by that a polymer gel that changes its volume depending on temperatures is used, and that a colorant and an infrared absorbing material are included in the polymer gel. A light control body formed by using this kind of light control material can control the transmittance of heat rays (near-infrared rays) in response to temperature due to the behavior of the infrared absorbing material, and also the transmittance in the visible light range can be controlled by the colorant. However, this kind of light shielding material has a problem that it is not possible to optionally and easily control the light transmittance in an arbitrary wavelength range in a sufficiently wide wavelength range from the visible light range to the near-infrared range.
Patent Document 5 discloses an electrochromic thin film consisting of a niobium oxide, and describes that the electrochromic thin film shows an excellent light controlling property in a wide wavelength range. However, when an inorganic oxide of this kind is used as a light control material, complicated steps need to be carried out to produce a light control element, thus leaving a problem for practical application.
With respect to the light control material for controlling the light transmittance in the infrared range, for example, Patent Document 6 discloses a material containing a diimonium salt compound having an infrared absorption and a polyester; Patent Document 7 discloses a coating liquid containing a dioxadinaphthopentacene compound having an infrared absorption and a binder resin; and Patent Document 8 discloses a heat shielding coating material using an infrared-absorbing perylene based pigment. However, those light control materials have a problem in dispersibility of the infrared absorbing compound in a binder resin, and due to uneven dispersion, uniform absorption characteristics may not be easily achieved.
Patent Document 1: Japanese Kokai Publication No. 2005-105131
Patent Document 2: Japanese Kokai Publication No. 2002-214653
Patent Document 3: Japanese Kokai Publication No. 2002-155215
Patent Document 4: Japanese Kokai Publication No. 2002-082364
Patent Document 5: Japanese Kokai Publication No. Hei-9-227860
Patent Document 6: Japanese Kokai Publication No. 2001-174627
Patent Document 7: Japanese Kokai Publication No. 2002-139619
Patent Document 8: Japanese Kokai Publication No. 2005-076019